---

Background and Aim: The rapid growth of the athletic training profession has been accompanied by an equally rapid increase in focus on basic and clinical research. Lateral ankle sprain (LAS) is an extremely common athletic injury. Despite extensive clinical and basic science research, the recurrence rate remains high. Chronic ankle instability (CAI) following LAS is hypothesized to predispose individuals to re-injury because of neuromuscular control deficits which result following injury. No investigation has been carried out on the existence of joint position deficits in the knee joint of patients with CAI. In this study, joint position sense (JPS) was evaluated in patients with CAI.

Materials and Methods: Ten female patients with CAI and ten healthy control subjects participated in this study. JPS was evaluated by reproduction of the angles in two standing and sitting positions, and in each position two target angles were tested. The knee joints in both lower limbs of patients and the dominant knee-limb of healthy subjects were evaluated. The knee angles were measured by using a system comprised of skin markers, digital photography, and Auto CAD software. Absolute error was considered as a dependant variable.

Result: There were no significant differences between the knee JPS of dominant leg in healthy subjects and both knee joints of patients. There were also no significant differences between knee JPS in two standing and sitting positions and in two different target angles (p>0/05).

Conclusion: The result of this study suggests that subjects who have CAI do not have deficit in knee JPS when tested in sitting position and also under functional weight bearing conditions.  

---

Background and aim: The ability to maintain upright stance is essential in gait and initiation of voluntary movements that are vital not only for sport but also for activity of daily living .Lateral ankle sprains are common in athletes and are most prevalent in jumping sports such as volleyball , football and basketball .Although these injuries are common after direct contact. It may occur in non contact mechanism such as landing from a jump. Neuromuscular control plays a major role in dynamic joint stability. Most of ankle joint injuries occur in jump-landing task and at the end of sport activitiesparticularly when the athlete is fatigued. Our purpose was to evaluate the effects of ankle muscle fatigue on dynamic postural stability in jump landing task. 

Material and methods: Twenty two healthy women athletes (age:22.8±1.7 years, height:160.3±4.9 cm and weight:56.2±5.8  kg) volunteered to participate in this study .Two test sessions were done with a rest period of one week between them . During each session, effect of one group of ankle muscles (sagital or frontal movers) on dynamic postural stability was assessed. Postural stability was evaluated for 5 seconds after landing on force plate by postural stability indices ( Medial/Lateral, Anterior/Posterior, Vertical and Dynamic Postural Stability Indices) before and after isokinetic fatigue of ankle muscles.

Results: The finding indicate significant increase in all stability indices after isokinetic fatigue of ankle muscles (p<0.05).

Conclusion:These results indicate that isokinetic fatigue of ankle muscles significantly decrease postural control ability in healthy women athlete. 

---

Background and Aim: Muscular fatigue is common problem that an athlete faces repeatedly during sport competition or therapeutic exercise. Undoubtedly¸ fatigue affects the precision of subjects’ performance and limits the range of physical and sport activities. Muscle fatigue advantages and disadvantages have been reviewed in many previous studies. To challenge this controversy fatigue evaluation requires reliable, stable and precise methods of analysis itself. Researches on muscle strength and subject’s perception of fatigue have been done in many studies. Therefore researchers in this study focus on temporal stability of both subjective perception of fatigue and produced muscle torque after fatigue.
Materials and methods: Fifteen healthy female between 20-30 years of age, who at least had some nonprofessional light sporting activities once a week, volunteered in this research. Each of volunteers was evaluated in 3 different sessions. The first session was to familiarize the volunteers with the Isokinetic tests. For the main test, each of the volunteers was evaluated once and then after one week interval. At each session after warm up, perceived fatigue was measured using Visual Analog Scale. Then Average peak torque and average power maximal concentric Isokinetic of quadriceps were measured at the velocity of 60 degrees per second. To perform the fatigue protocol, subjects were asked to perform successive maximal quadriceps contractions until the three subsequent quadriceps torque output drop below 50 percent of maximal torque output. Afterwards, for re-measurement average peak torque, average power and perceived fatigue were evaluated similarly.
Results: The interaclass correlation coefficient (ICC) of average peak torque¸ average power and visual analog scale before performing fatigue protocol were calculated %81.6, %87.4 and %47.9 respectively. The repeated ICC after fatigue has estimated %59.9 ¸%64.4 and %96.6 respectively.
Conclusion: This research demonstrated that Isokinetic temporal stability parameters were high before fatigue. In other words, both torque and power are reliable in two repetition times in a session, as well after one week interval between. After fatigue the stability rate of torque and power recorded by Isokinetic were repeatable and this repeatability has been moderate to high. However VAS showed a completely opposite results, in which before fatigue the stability of imagined local fatigue perception has been very low and was not significant, although after fatigue the VAS showed high repeatability.

---

 Background and Aim: The common mechanism for lateral ankle sprain is inversion, plantar flexion, or the combination of both, if untreated successfully can lead to chronic ankle instability. It seems that the foot position, while touching the ground, has an effective role to cause ankle sprain. Thus it is possible to prevent ankle sprain through limiting foot position. Therefore the aim of this research is to study the effect of plantar flexion and eversion on mediolateral ground reaction force while landing in individuals who suffering from functional ankle instability.

Materials and Methods: In this case-control research study 32 subjects (17 subjects with unilateral functional ankle instability (FAI) and 15 control subjects), aged from 18 to 35 years, were tested. All subjects in instability group were selected by the orthopedic physician, then the anterior drawer and talar tilt tests were  performed for diagnosis of functional ankle instability and other physical examinations. Control group were matched with instability group by age, weight, height, gender and body mass index. The subjects standing with single leg on a 40 cm high platform in 25 cm front of a force-plate while the test leg relaxed and non-weight bearing. The subject landed on the test leg on the center of the force-plate. The subjects landed according to four types of position: A: neutral position of ankle and lateral foot wedge, B: neutral position of ankle, C: positive heel and lateral foot wedge and D: positive heel. 

Results: Among control group, medial ground reaction force increased in the "C" position relative to "B" position (p=0.007) and "C" position relative to "D" position (p=0.018). In FAI group, lateral ground reaction force increased in "C" position relative to "B" position (p=0.001) and "C" position relative to "A" position (p=0.002). Also in FAI group medial ground reaction force decreased in "D" position relative to "A" position (p=0.014). 

Conclusion: According to the findings, applying lateral foot wedge, while the ankle is in plantar flexion, increases the mediolateral ground reaction forces. Based on the results, position of plantar flexion is more possibly effective than inversion in ankle sprain. According to the study, the lateral foot wedge in ankle plantar flexion position may be more effective than in neutral one to change mediolateral ground reaction forces. 

---

Background and Aim: Core stability is the ability of the lumbopelvic- hip complex to prevent buckling of the vertebral column and return it to equilibrium following perturbation. It has been demonstrated that trunk muscle activity occurs before the activity of the prime mover of the limb. Core stability is seen as being pivotal for efficient biomechanical function to maximize force generation and minimize joint loads in all types of activities ranging from running to throwing. The aim of this study was to examine the correlation between core stability and lower extremity function in female athletes.

 Materials and Methods: Thirty volunteer female athletes with mean age (SD)=23(3.8) years old, participated in this study. They performed two series of tests: core stability tests (hip isometric abduction and lateral rotation, double leg lowering, trunk extension – flexion and left and right lateral flexion endurance, and double leg lowering), and lower extremity function tests (star excursion balance tests in three directions, vertical jump, single and triple hopping, stairs sprinting, 6 m hopping, and shuttle run).

Results: The results of this study showed that the strength of hip isometric abduction with stairs sprinting, 6 m hopping , and with star excursion balance test in three directions had r=-0.430, r=-0.367and r=0.515 respectively and all significant. Also , right lateral flexion endurance with shuttle run (r=0.367) , double leg lowering with vertical jump (r=0.42), trunk extension endurance with vertical jump (r=-0.404) ,were significantly correlated. In the other items there were no relationship between core stability and lower extremity function (p>0.05).

Conclusion: There is a relationship between core stability and lower extremity function but studies have not supported them. However, the data showed that core stability is moderately too weak related to lower extremity function, core stability could not be measured with these tests and they are not good indicators for lower extremity function. Evaluation of the core should be dynamic, and compromise assessment of the specific functions which specialize for athletic groups.

---

Background and Aim: More recently, attention has turned to the role of proximal structures in function of lower limb. Decreased lumbo-pelvic (or core) stability has been suggested to contribute to the etiology of lower extremity sport injuries. This is largely due to the closed chain nature of athletic activities. Groin pain is a common complaint for athletes participating in sports such as soccer. Adductor-related groin pain was the most common primary entity in soccer players. Therefore, the aim of this study was to compare of core stability between male soccer players with and without hip adductors strain. Various studies have been done for treatment and prevention of recurrent of this lesion and the most important thing in these studies was to keep the integrity of  the core stability.
Materials and Methods: Fifty professional soccer players (25 healthy and 25 with adductors strain. mean age: 21.32±2.73) was studied. Core stability was compared among them by 5 endurance and functional tests. Endurance of back extensors, trunk flexors and lateral flexors were tested by Modified Biering-Sorensen and Mc.Gilltests.In current research, the Double Leg Lowering test is applied to measure the function of the oblique abdominals muscles and the Single Leg Squat test is applied to measure the function of hip abductor and external rotators muscles.
Results: Endurance of back extensors, flexors and lateral flexors were significantly lower in the injured soccer players in comparison with the healthy players. Significant decrease in the function of oblique abdominal muscles, hip abductor and external rotator muscles were founded in the injured players (p<0.05).
Conclusion: Decrease of endurance and function in the trunk muscles is probably an important risk factor for hip adductors strain injuries in the soccer players. Increasing the endurance of the core muscles can be reduced the occurrence of hip addactors strain. 

---

Background and Aim: With regard to importance of the role of balance in performance of daily activity especially in exercise activity and necessary to identify the factors that influence the balance, the purpose of this study was to survey the effect of lower limb muscle fatigue on balance in elite young athletes.
Materials and Methods: For this purpose, 15 young elite swimmers with a mean age and body mass index 17±0.7 and 21.62±0.5 during the two test phase, were studied. All participants performed the postural Stability and limit of stability tests in six for each test (three repetitions before and three repetitions after fatigue protocol by Wingate test)on the balance Biodex system. Values obtained by the system of the total , anterior - posterior, medial - lateral, anterior, anterior - right, anterior- left, posterior, posterior - right and posterior left index, were analyzed using paired sample t-test(P0.05).
Results: Results showed that fatigue caused a significantly influence the anterior - posterior, medial - lateral, posterior, left and posterior –left index.
Conclusion: With considering the specificity of training principle, the results can be helpful in the design of exercises involving the lower limb muscles in the specific direction. Keyword: Balance, Limit of stability, Fatigue, Athlete.

---

Abstract

Background and Aim: The Action Observation stimulates mirror neurons. It is the effective acquisition of skills, motor learning and memory formation and this feature can be used to treat injuries such as stroke. The aim of this study was to investigate the effect of action observation on the symmetry of weight distribution in lower limbs and stability indices in semi-dynamic stability.

Materials and Methods: This study was conducted in 91 healthy male and female non-athletes aged 20 to 45 years. Data were collected through questionnaires and clinical examinations. Subjects were randomly assigned to men and women with and without film observation. A 3-minute short film was preapared to stimulate mirror neurons in the standing position on the symmetry weight measurement system and Biodex platform system. In film observation group, before and after viewing the film, distribution of weigh bearing on the right and left sides, and dynamic stability indices in two stability levels of 5 and 8 were measured and calculated indices of total, anterior - posterior and medio- lateral indices were obtained. In without film observation group, measurements were performed at the similar time as a film observation group.

Results: Percentage weight distribution showed no significant difference between the two groups. The comparison of percentage changes between two groups showed that observation of the film improved significantly total index (p <0.002) and anterior – posterior index (p <0.018) in the stability level of 5. Analysis of the results in the separately men and women groups, showed the significant improvement of these parameters only in women group after film observation regardless of film observation, the percentage changes of stability indices showed no significant differences in men groups.

Conclusion: Action Observation (by activating the mirror neurons) can be effective methods to improve the balance standing of healthy people on the stable and unstable surfaces. Significant improvement stability indices in women after viewing the film, may suggest the greater sensitivity of women's mirror neurons related to men.

Keywords: Mirror Neurons, Action Observation, Symmetry of Weight Distribution, Dynamic Stability, Stability

---

Bachground and Aim: Ankle sprain is one of the most common injury among the athletic injuries. Around 70-80% of these injuries tend to be chronic. Despite extensive clinical and basic science research, the incidence of Chronic Ankle Instability(CAI) has not significantly reduced. Because the causes of CAI is not quite clear, the rehabilitation still deals with great challenges . one of the treatment methods which has been under special attention for this injuries is Kinesio Taping(KT). In this study, effects of three KT methods on performance in athletes with CAI was investigated .

 

Materials and Methods: Thirty male athletes (futsall, football) with CAI participated in this study. The KT was used in three distinct times with three different methods (mechanical, functional and ligament- Tendon Correction) for these people and their short- time effects on functional performance of lower limb was evaluated. This evaluation was done thorough two functional performance test (Star Excursion Balance Test and Figure of 8 Hop Test).

 

Results: In taping with the aim of functional and mechanical correction, functional performance after KT dramatically improved but in taping with the aim of Ligament-Tendon correction functional performance did not change significantly after taping.

 

Conclusion: The result of this study suggests that functional and mechanical correction have the significant effect on functional performance of futsaland football athletes with CAI , the ligament-tendon correction has not significant effect.

 

Keywords: Chronic ankle instability, Kinesio tape, Functional performance tests.

---

Background and Aim: Many studies investigated the effect of ankle-foot orthosis on reducing the incidence of sprain. In this study the influence of elastic and semirigid stirrup type orthosis on the onset latency of peroneus longus muscle activity as the most important support of ankle- foot region in response to sudden perturbation was assessed in healthy group and athletes with functional ankle instability.

 

Materials and Methods: Thirteen healthy female athletes and 10 female athletes with functional ankle instability (17 to 27 years old) were perturbed unexpectedly by a custom made ankle perturbation system in frontal plane under three conditions of without orthotics, using elastic orthosis, and using semirigid stirrup-type orthosis. Simultaneous recording of electrical activity of peronus longus muscle was performed with surface electromyography.

 

Results: The results showed the significant differences between muscular latency of injured and control groups without orthosis (P=0.018). The onset latency reduced using each type of the orthoses in injured group but it was not significant (P>0.05).

 

Conclusion: Although the latency time of peroneus longus muscle response delay didn’t show significant reduction using orthoses in injured group, it seems that using orthoses leads to proprioception improvement and sensiomotor control increasement by stimulation of cutaneous mechanoreceptors.

 

Key words: Functional ankle instability, Invertory perturbation, Electromyography, Orthosis

---

Background and Aim : Trauma or micro-trauma over prolonged period of time can lead to

  pathoanatomical changes and passive instability of the sacroiliac joint. These subjects often reluctant to bear full weight through the impaired side of the pelvis. The aim of this study was to investigate the effect of exercise therapy on symmetric distribution of weight in sacroiliac joint instability in standing and walking through Alfoot device.

 

Materials and Methods : In this study, 17 subjects with sacroiliac joint instability with age range of 20-40 years were selected by simple sampling. Subjects performed a single session of training that involve five tasks in 3 sets, including sitting on gym ball, lying on gym ball, quadruped, standing near wall and standing on tilt board. Before, immediately after, 5 and 10 minutes after intervention , scanning the both feet were recorded during standing and walking.

 

Results : The amount of weight on both feet in bipedal stance position were significantly different before and immediately after the intervention. But this difference , 5 minutes (p =0.058) and 10 minutes (p =0.110) was not significantly different after exercise therapy. The pressure on the middle part of the foot during walking significantly increased immediately after the intervention and it continues up to 10 minutes .

  

Conclusion : The results of this study suggest that training of lumbopelvic muscles can be an effective way to improve weight distribution on the affected side in patients with sacroiliac joint instability .

---

Background and Aim: Fractal dimension (FD) as a measure of system complexity and a chaos and nonlinear dynamics tool has appeared successful in distinguishing subjects with different specifications such as proficiency level. The purpose of this research was to evaluate the capability of FD analysis of postural stability in distinguishing elite Wushu sportsman for dispatching to various competitions.

Materials and Methods: Eight elite and eight non-elite Wushu sportsmen from Talou section participated in this research and performed a difficult balance motion called “backward balance”. Center of pressure (COP) traces were recorded and Higuchi algorithm has been used to obtain fractal dimension of COP displacement time series. Average of FD of two groups were compared with an unpaired t-test.

Results: In both directions of anterio-posterior (AP) and medio-lateral (ML), average values of FD in elite group were significantly more than non-elite group (p<0.05). Subsequently, implementing a receiver operating characteristic (ROC) analysis indicated that FD analysis method performance is very good in AP direction (Area under the curve or AUC=0.938) and good enough in ML direction (AUC=0.668).

Conclusions: Postural control system acts more complex in elite group because of their more proficiency. FD analysis of COP time series could help coaches in choosing elite Wushu sportsman even among a group of skilled Wushu sportsmen. 

Keywords: Wushu, Postural stability, Fractal dimension, Receiver operating characteristic (ROC), Center of pressure (COP)

---

Background and Aim: Standing stability is resulted by normal functioning of various neuro-muscular and musculo-skeletal systems. Patients with below knee amputation cannot use ankle strategy due to limb loss and they have to rely on other mechanisms to improve their standing stability. The effect of prosthesis foot on standing stability of patients with below knee amputation is not well understood. Therefore, the aim of this study was to evaluate the stability of below knee amputees and determine the influence of prosthesis foot on stability

Materials and Methods:  Fourty subjects participated in this study. Participants were divided into three groups including:  (a) normal individuals, (b) amputees using SACH foot and (c) amputees using single axis foot. The stability of subjects was evaluated by use of a Kistler force plate. The subjects were asked to stand on the force plate for one minute and look forward with their hand at their sides. The stability was evaluated by use of some parameters such as excursion of Center of Pressure (COP) and path length and velocity of COP in mediolateral and anteroposterior directions. The difference between the stability of the subjects was determined using One-way ANOVA and Post Hoc test.

Results: There was a significant difference between stability of the three groups during standing with regard to path length and velocity of COP in mediolateral and anteroposterior directions (P < 0.05). No significant difference was reported with regard to all of the measured parameters when comparing normal individuals and amputees with single axis foot (P >0.05).

Conclusion: Below-knee amputees standing stability who are using single axis foot have the same standing stability compared to normal subjects; moreover, stability of amputees who are using SACH foot was surprisingly better than normal subjects in some of the parameters including path length and velocity of COP in mediolateral and anteroposterior directions.

Keywords: Standing stability, Below knee amputation, SACH foot, Single axis foot, Force plate

---

Background and Aim: This study was conducted dueto the limited results of past studies in relation to postural control in children with developmental coordination disorders and the importance of postural control with the ability to integrate the vestibular, visual and somatosensory inputs. In this study the postural control of the children with Developmental Coordination Disorder (DCD) and their normal peers was compared under the reduced or the conflicted sensory input conditions.

Materials and Methods: Twenty two children with Developmental Coordination Disorder (16 males, 6 females with mean age of 7 years old and 9 months, SD 1 year and 5 months) and 19 children with normal motor development (13 males, 6 females, with mean age of 6 years and 11 months, SD 1 year and 1 month) were evaluated. Standing balance, sensory organization and motor control strategy were evaluated using the sensory organization test (SOT).

Result: The results showed that the children with DCD had poorer function than the normal children in the composite equilibrium (p&le; 0.001), visual ratios (p=0.005) and vestibular ration (p=0.002). There were no meaningful differences between groups in their average somatosensory ratio. Additionally, children with Developmental Coordination Disorder had lower motor strategy scores than the normal children when they were forced to depend on vestibular cues alone (p < 0.05). The children with Developmental Coordination Disorder had deficits in standing balance control in conditions that included reduced or conflicting sensory signals. The visual and vestibular systems tended to be more involved in contributing to the balance deficits than the somatosensory system. Moreover, children with Developmental Coordination Disorder were tended to use hip strategy excessively when forced to rely primarily on vestibular signals to maintain postural stability.

Conclusion: In order to improve the postural control in the patients, the rehabilitation protocols should focus on the sensory-motor deficits.

Keywords: Postural control, Postural stability, Developmental Coordination Disorder

---

Background and Aim: Whole body vibration (WBV) is a new therapeutic modality which improves muscle function, proprioception and postural control by creating an oscillatory mechanical stimulation. The aim of this research was to investigate the immediate effect of WBV on postural control in young adults.

Materials and Methods: In this quasi-experimental study, 22 healthy subjects were participated as a single group. Non-probability simple sampling method was used. Subjects were treated with 4 minutes WBV bout. The subjects repeated four times a 60-s light exercise program according to instructions which was shown by the therapist. During the vibration intervention, the vibration frequency increased in 1 minute intervals from 15 Hz for the first minute to 30 Hz for the last minute. Postural control indexes were recorded using the Biodex Balance system in situations of two leg standing with open and close eyes that included overall stability index (OSI), anterior-posterior stability index (APSI), medial-lateral stability index (MLSI) . In order to analyze the data, paired t-test was used.

Results: The results indicated that in the case of standing on two legs with eyes open, OSI and MLSI were statistically significant (P = 0.02; P = 0.01, respectively) and with eyes closed, OSI, APSI and MLSI were statistically significant (P = 0.000; P = 0.001; P = 0. 001, respectively).

Conclusion: Four minutes WBV bout can induce improvement of postural control and balance in young adults.

Keywords: Whole body vibration, Balance, Young adults, Stability